Synthetic closure and manufacturing process thereof

ABSTRACT

A plastic foamed synthetic closure for use with liquid bearing containers which closely simulates natural cork products is realized by incorporating color concentrates into the polymer melt and forming the color concentrates into elongated streaks. The desired emulation is further enhanced by arcuately pivoting the foamed plastic material during the production to form curved or sinusoidal-shaped streaks. This invention also provides manufacturing methods for mass producing individual products in a continuous motion casting system wherein fully complete products are formed in polymer casting members, which receive foam material exiting from the die and allow the foamed material to be formed in a continuous operation in the casting members. Finally, the present invention also teaches a unique system for maintaining and delivering carbon dioxide in its supercritical phase for use as a blowing agent.

This application claims benefit of Provisional Application Ser. No.60/105,073 filed Oct. 21, 1998.

TECHNICAL FIELD

This invention relates to extruded elastomeric foams incorporatingextremely fine, uniform cell structures, constructed for employment as asynthetic closure for liquid bearing vessels and, more particularly, toa process for producing such products as well as the product itself.

BACKGROUND OF THE INVENTION

For many years, the wine industry has relied on natural cork as the soleproduct to seal wine bottles. However, there are several negativeaspects which are inherent in the use of natural cork as a closure, allof which are disturbing to the industry and to consumers.

One of the principal drawbacks of natural cork is cork taint. Cork taintexists because of a chemical compound (2,4,6-trichloranisole or TCA),which is found naturally in the cork bark. This taint effects the odorand flavor of the wine and accounts for as much as 50% of the spoilageof all wine bottled with natural cork.

Another problem is broad diversity that exists for natural cork quality.In an attempt to deal with this problem, the cork industry has adoptedstandards which are subjective at best and generally relate to thenumber of lenticels, cracks and their sizes, overall aesthetics, smellsand functionality, all of which are subject to the growing andharvesting conditions experienced in the cork growing regions of theworld. Each individual cork is therefore unique unto itself in all ofits characteristics and possesses a wide range of variations. Thesevariations may cause as much as 20% spoilage of bottled wine, dueprincipally to such physical characteristics as non-circularcross-sections, cork size, density, and cell sizes internal to thenatural cork that cannot be seen during manual grading. Theseuncontrollable variations often cause leakage and unwanted oxidation ofthe wine.

A further drawback of natural cork is the fact that cork is an extremelylimited resource. Natural cork bark is harvested from the cork oak whichis only able to replenish itself on the order of once every 10 years.This, coupled with the fact that new plantings require 30 years to cometo maturity, leaves the natural cork industry with limited ability toincrease productivity to meet the demand of an ever-increasingcommodity.

A final drawback is the cost of natural cork. Due to its limitedavailability, especially for higher quality products, and increasingdemand, the cost of using cork products in the wine industry has seen aconstant rise over the years. This trend probably will not shift as itis a limited resource and is a very labor intensive industry.

In spite of these difficulties and drawbacks, a majority of all winebottles utilize a natural cork for their closures. As a result, both thewine industry and the consumers have accepted cork closures and havetolerated a certain level of defective product. As a result, efforts todevelop a synthetic closure acceptable to the wine industry andconsumers have not materialized, except in the area of screw caps, madefrom aluminum and plastic, and a small segment of molded closures.However, in spite of the industry's desire to eliminate the inherentproblems found with cork closures, prior to the present invention, noclosure has been developed which is (1) able to maintain the ceremony ofopening the wine bottle, (2) has none of the negative attributes ofnatural cork, (3) is aesthetically acceptable, (4) meets all thephysical requirements of a high speed mass bottling, (5) is consistentlyreproducible, (6) meets all regulatory criteria, and (7) is costeffective in a mass production setting.

Therefore, it is a principal object of the present invention to provideclosure means for containers which is manufacturable from syntheticmaterials and effectively closes and seals any desired bottle,container, package and the like.

Another object of the present invention is to provide a syntheticclosure having the characteristic features described above which ismanufacturable on a continuing production basis, thus providing lowermanufacturing costs compared to natural closures and satisfying industryrequirements for a removable bottle stopper which is produciblesubstantially more economically than cork closure/stoppers.

Another object of the present invention is to provide a syntheticclosure having the characteristic features described above which meetsor exceeds all of the requisite physical characteristics found innatural closures or stoppers such as cork.

A further object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich is capable of simulating all of the visually aesthetic and tactilecharacteristics found in natural stoppers, such as cork, so as to beeffectively a substitute for cork stoppers or closures for the wineindustry, particularly its ends users in both appearance and feel.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich is capable of being employed in conventional bottling equipmentfor being inserted into a bottle container without experiencing anyunwanted physical damage.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovethat can be substituted for a cork stopper in wine bottles, providingall of the desirable characteristics of conventional cork stoppers whilealso being removable from the bottle in the conventional manner withoutbreaking.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described above,which is physiologically neutral, capable of being sterilized, as wellas capable of being formed to visually simulate any desiredclassification of natural cork.

A further object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich is odorless, remains odorless in position, is tasteless, and onlyabsorbs limited amounts of water.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich is unaffected by diluted acids and bases as well as unaffected bymost oils.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich does not shrink, does not age, does not absorb mold or fungus, andresists damage from insects.

Another object of the present invention is to provide a syntheticclosure or stopper having the characteristic features described abovewhich can be mass produced on a continuing basis and eliminates anyspoilage of wine due to cork taint.

Other and more specific objects will in part be obvious and will in partappear hereinafter.

SUMMARY OF THE INVENTION

By employing the present invention, all of the difficulties anddrawbacks found in the prior art have been eliminated and an extrudedsynthetic closure capable of being manufactured continuously andproviding a low cost product is achieved. In addition, the syntheticclosure of the present invention possesses all of the physical anddesirable visual characteristics required by the wine industry. As aresult, the present invention achieves a synthetic closure usable in thewine industry as a bottle closure which is virtually equivalent in allrespects to a natural cork closure.

One of the principal requirements imposed upon a closure for winebottles is its sealing capability. In the wine industry, high speedcorking machines are employed which subject the closures to extremeforces. These corking machines typically utilize a plurality ofcompression jaws, typically ranging between two and four, which radiallycompress the closure from its normal diameter to a substantially smallerdiameter, which is about one third of its original size. Then, byemploying a plunger or ram, the closure is forced from the jaws in thecompressed mode directly into the neck of the bottle, wherein theclosure is able to expand to its original diameter, sealing the bottle.

As a result of the construction of the compression jaws, a knife edge iscreated on each jaw member. Consequently, between two and four separatelocations incorporate an inherent knife edge formed on the jaw element.These knife edges often crease or score the outer surface of theclosure, unless the closure is sufficiently elastic in nature to be ableto resist this scoring or creasing action. In many instances, creasingor scoring of the closure causes the bottle of wine to leak or allowsthe transfer of the outside atmosphere into the bottle, causingoxidation of the wine and rendering the wine unpalatable.

In the present invention, the formulation employed for attaining asynthetic closure achieves a resulting product which is capable ofresisting the compressive forces imposed on the closure by the corkingjaws, as well as resisting any permanent scoring or creasing of theouter surface. In addition, the synthetic closures of the presentinvention also possess a high compression recovery rate, enabling thesynthetic closure of the present invention to return to at least 960/oof its original diameter upon exiting the jaws of the corking machines.In this way, the synthetic closure of the present invention is capableof providing all of the desired attributes for attaining a viableclosure for the wine industry, enabling the closure to be employed innormal production equipment for completely sealing the wine bottle uponinsertion therein.

Another feature of the present invention is the ability to attain asynthetic closure which is capable of receiving and cooperating with anydesired surface treatment. In this way, the extraction forces requiredto remove the synthetic closure of the present invention from a winebottle is easily controlled.

Extraction force is typically defined as the force a person of ordinarystrength must exert to remove the closure from the one bottle withoutundue stress or strain. Typically, between about 40 pounds and 80 poundsof pulling force is required. In the present invention, the syntheticclosure defined herein is capable of easily meeting this standard, dueto the compatibility of the formulation of the present invention withconventional surface treatments. In addition, this compatibility alsoenables the closure of the present invention to incorporate any othertreatment typically required for controlling insertion depth.

Another feature of the present invention is the attainment of asynthetic closure which has a neutral smell or aroma and does not impartany objectionable fragrance, smell or aroma to the wine itself. In thisway, the normal wine fragrance is not disturbed and the flavor sensationassociated with a particular vintage or type of wine is not negativelyimpacted. Furthermore, the present invention does not impact unwantedflavors to the wine, allowing the wine to remain with all of its naturalflavor.

In addition to attaining all of these physical attributes, theformulation of the synthetic closure of the present invention also needsor exceeds all requirements of the Food, Drug and Cosmetic Act, enablingthe closure to be used in direct contact with food products.Furthermore, in accordance with the present invention, unique colorconcentrates are capable of being integrated into the formulation. Inthis way, the synthetic closure of the present invention may beformulated with a visual appearance virtually identical to natural cork.In this regard, the growth rings typically associated with natural corkare able to be emulated by the synthetic closure of the presentinvention. Furthermore, if desired, any coloring can be imparted intothe synthetic closure to provide a unique visually distinctive product,as well as provide a surface upon which any printed indicia, such aslogos, dates, characters, etc. can be applied to the surface of thesynthetic closure.

The invention accordingly comprises an article of manufacture possessingthe features, properties, and relation of elements which will beexemplified in the article hereinafter described, as well as the severalsteps in relationship of one of more steps with respect to each of theother and producing the article of manufacture defined herein, with thescope of the invention being indicated in the claims.

THE DRAWINGS

For a fuller understanding of the nature and object of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a cross-sectional side elevational view of a portion of thelinear flow extrusion device employed in the present invention;

FIG. 2 is an enlarged cross-sectional side elevational view of theextrusion die employed in the extrusion device of the present invention;

FIG. 3 is a top plan view of the extrusion die of FIG. 2;

FIG. 4 is a diagrammatic side view depicting the extruded foam productof the present invention exiting the extrusion die for cooling andarcuate pivoting movement;

FIG. 5 is an end view of the pivot inducing systems employed and shownin FIG. 4;

FIG. 6 is a diagrammatic view of a pumping system preferably employedfor delivering the blowing agent to the desired location in the presentinvention;

FIG. 7 is a cross-sectional side elevation view depicting the preferredconstruction of the blowing agent injector;

FIG. 8 is a diagrammatic top plan view of a continuous motion castingsystem of the present invention for use in mass producing completelyfinalized finished products;

FIG. 9 is a greatly enlarged top plan view of the polymer receiving zoneof the continuous motion casting system of FIG. 8;

FIG. 10 is a greatly enlarged top plan view of the product dischargezone of the continuous motion casting system of FIG. 8;

FIG. 11 is a greatly enlarged top plan view of the polymer receivingzone of the continuous motion casting system of FIG. 8 wherein acoextrusion die is employed;

FIG. 12 is a cross-sectional plan view of a plurality of polymer castingforms of the continuous casting system of FIG. 8 depicted in mating,cooperating engagement with each other;

FIG. 13 is a cross-sectional plan view of polymer casting forms depictedin mating engagement; and

FIG. 14 is a cross-sectional side view of the mating polymer castingforms of FIG. 13.

DESCRIPTION OF THE INVENTION

By employing the present invention, all of the drawbacks anddifficulties of the prior art are overcome and an extruded, medium tohigh density, uniform, extremely fine cell elastomeric, synthetic foamclosure is achieved. In accordance with this invention, a uniqueformulation and extrusion process is provided which completely overcomesthe inefficiencies of prior art attempts to achieve a synthetic closureacceptable to both the industry and consumers. By employing theteachings of the present invention, the physical and visual attributesof natural cork are provided without the negative aspects of naturalcork products.

In order to achieve the advancement attained by the present invention, aunique formulation is employed. By employing the present invention, anextruded, uniform, extremely fine cell, elastomeric foam closure isattained having a medium to high density of between about 100 and 500kg/m³. In order to attain this result, the elastomeric foam closurecomprises a blend of plastic polymers, additives, color concentrates,and a combination of physical and chemical blowing agents to produce amedium or low density closed cell foam rod with all of the desiredphysical and aesthetic attributes.

In the present invention, the preferred polymers are selected from oneor more groups of materials compatible with one another and meeting FDAguidelines for direct food contact. These groups include homopolymers,copolymers (including random copolymers, alternating copolymers, blockcopolymers or grafted copolymers), terpolymers, interpolymers, as wellas a group of compounds known to those skilled in the art asthermoplastic elastomers (TPE's) and thermoplastic olefins (TPO's).These thermoplastics include polyurethanes, elastomeric alloys,thermoplastic copolyesters, styrene block copolymers (such as SEBS, SBS,styrene isoprene) and thermoplastic amides.

The preferred combination of the present invention comprises apolyethylene homopolymer, polyolefin elastomer and an ionicallycross-linked resin. It has been found that this blend, eitherindependently or in combination with all of the other components orformulations of this invention, yields a foam structure capable ofmeeting the demands of the wine industry.

One of the principal requirements that must be met by a synthetic wineclosure is the elastic recovery characteristics which will enable thesynthetic closure to withstand creasing and scoring from the jaws of thehigh speed corking apparatus used in the wine industry for massbottling. In order to attain a high quality synthetic closure inaccordance with the present invention, the preferred formulationcomprises one or more homopolymers ranging between about 10% and 60% ofthe entire composition. More preferably, it has been found that thehomopolymers should comprise between about 20% and 40%, with 30% beingoptimum. Generally, the percentage of thermoplastic elastomer employedin the composition ranges between about 10% and 60%, preferably betweenabout 20% and 40%, with 30% being optimum. Finally, the percentage ofthe ionically cross-linked resin ranges between about 10% and 60%,preferably between 20% and 40%, with 30% being optimum.

In accordance with the present invention, a synthetic bottle closure isattained which possesses all of the physical characteristics to enablethe synthetic closure to be virtually equivalent to the desirablecharacteristics of natural cork. In addition, in order to provide afurther enhancement to the present invention, the preferred embodimentis constructed in a manner which visually simulates the appearance ofcork. As one aspect of this construction, color concentrates areincorporated into the synthetic cork formulation in a manner whichemulates the visual appearance produced by the “growth rings” typicallyfound in cork closures.

Preferably, the color concentrate utilized to obtain the desired “growthring effect” is a combination of two distinctly different hues with eachof these hues being achieved by using different viscosity polymers aspart of a pigmenting system which is compatible with the othercomponents of the synthetic closure. For example, light brown and darkbrown pigmenting polymers can be employed, with the light brown polymershaving a melt flow index of between about 6 and 10, while the dark brownpolymer have a melt flow index of between about 16 and 20. Thisdisparity in melt flow indices and, hence the viscosity of the polymers,produces a mottling effect within the extruder.

As shown in FIGS. 1-5, the system of the present invention employs diehead 20 which comprises linear flow extrusion device 22 and die 24. Inaddition, linear flow extrusion device 22 comprises apertures orpassageways 23 formed therein for controlling the flow of the polymermelt therethrough.

As diagrammatically depicted in these figures, color concentrates 25 areincorporated into the plastic melt 26. Mottling characteristics producedby the pigmented polymers or concentrates 25 are transformed into randomlinear stripings or strips 27, which may have different widths as thecolor concentrates 25 and polymer melt 26 pass through apertures 23 oflinear flow extrusion device 22. By employing this construction, thegrowth rings of the natural cork product are simulated.

In addition, as is more fully detailed below, the preferred process ofthe present invention utilizes oscillating motion on the downstreamportion of the extrusion to continuously manipulate the extruded foamrod in a slight back and forth motion, producing slight “wiggles” orinterruptions in the linearity of the streaks. In this way, the “growthring effect” is further emulated and enhanced.

Other components incorporated into the composition of the presentinvention comprises one or more suitable and compatible nucleationagents.

Preferably, the nucleating agent is selected from the group consistingof titanium oxide, silica, talc, calcium silicate, barium sulfate, anddiamatious earth. Although these compounds are preferred, other agentsknown to those skilled in this art may also be used.

Generally, the nucleating agent comprises between about 1% and 10% byweight of the weight of the entire composition and, typically, betweenabout 2% and 8% by weight of the entire composition. In addition, it hasbeen found that 5% of the composition is preferred.

Furthermore, a chemical blowing agent is also preferably employed in theformulation of the foamed rod of the present invention. Preferably, anendothermic alkali carbonate mixture is employed which provides amultifunctional purpose as the chemical makeup and particle size isadvantageous in nucleating the foam even beyond the capability of thenucleating agent. This intense nucleation yields extremely fine cellsize in combination with the extreme atomization achieved by alsoemploying a physical blowing agent. Generally, the chemical blowingagent comprises between about 0.5% and 5% by weight of the weight of theentire composition, with between 1% and 30% being typically employed.However, in the preferred composition, about 2% by weight is employed.

As mentioned above, a physical blowing agent is preferably employed inaddition to the chemical blowing agent. It has been found that aneffective physical blowing agent may be selected from the groupconsisting of aliphatic hydrocarbons and inorganic blowing agents. Inregard to the use of aliphatic hydrocarbons as the physical blowingagent, it is preferred to employ one or more agents selected from thegroup consisting of methane, ethane, propane, n-butane, isobutane,n-pentane, isopentane and neopentane. In addition, the preferredinorganic blowing agent preferably comprises one or more agents selectedfrom the group consisting of carbon dioxide, nitrogen, water, air,helium, and argon. The most suitable of these blowing agents is liquidcarbon dioxide in its supercritical phase.

Generally, the physical blowing agent incorporated into the polymer meltranges between about 0.01% and 3% by weight based upon the weight of theentire composition. In addition, it has been found that between about0.05% and 2% by weight is effective, with between about 0.1% and 1%being preferred. These percentages will generally produce densities, ofthe final extruded, extremely fine cell elastomeric foam suitable for asynthetic wine closure on the order of 100 to 500 kg/m³, typically onthe order of between 150 to 300 kg/m³.

In addition to the blowing agents detailed above, other blowing agentsthat may be employed comprise one or more selected from the groupconsisting of nitrogen, carbon, water, air nitrogen, helium, and argon,Azodicarbonamic Azodiisobutyro-Nitride, Benzenesulfonhydrazide,4,4-Oxybenzene Sulfonylsemicarbazide, p-Toluene Sulfonylsemi-carbazide,Barium Azodicarboxlyate, N,N ′-Dimethyl-N,N ′-Dinitrosoterephthalamide,Trihydrazinotriazine, Aliphatic Hydrocarbons having 1-9 carbon atoms,Halogenated Aliphatic Hydrocarbons having 1-9 carbon atoms, AliphaticHydrocarbons having 1-9 carbon atoms, Aliphatic alcohols having 1-3carbon atoms and partially Hydrogenated Chlorocarbon andChlorofluorocarbons.

The Process

The conventional technique of foaming is well known to those skilled inthe art. However, one aspect of the present invention comprises a novelprocess which has been developed in order to achieve the desired finalproduct on a consistent, repeatable production basis. In carrying outthe process of the present invention, an extruder is employed whichcomprises a tandem single screw construction, typically a conventionalsingle screw extruded. However, preferably, a counter-rotating twinscrew extruder is employed utilizing screw designs that produce a highdegree of plastification in the first stage, without adding excess shearand temperature into the melt.

In accordance with the present invention, the physical blowing agent isinjected between the first and second stage. In addition, the secondstage includes an aggressive dispersive as well as distributive mixingsection which achieves the proper solubility of carbon dioxide in itssupercritical phase within the polymer melt, while maintaining thepressure requirements of carbon dioxide in its supercritical phase.

Injecting carbon dioxide as a blowing agent requires a novel pumpingsystem to accurately and consistently deliver carbon dioxide to theinjector in its supercritical phase. In the preferred embodiment, asdiagrammitcally depicted in FIG. 6, the delivery system comprises a dualcylinder syringe type pump 30 which incorporates a water cooled jacket.In addition, the carbon dioxide is stored as a liquid in tank 31 anddelivered to pump system 30 through tubing 32, all of which aresurrounded by water cooled jackets 33.

In the preferred construction, pump system 30 is retrofitted with a massflow meter coupled to a feedback loop with appropriate computer controlsto maintain the flow volume to within 0.1 ml/hr. The carbon dioxide flowfrom pump system 30 is carried in tubing 31, to a pre-pressure regulator34, and then delivered to the injectors of the extruder. All tubing 31used to carry this carbon dioxide is preferably surrounded by watercooled jackets 33. In this way, constant pressure above the pre-pressureset point of 2600 psi is maintained.

In this embodiment, pre-pressure is regulated through a diaphragm typevalve with a variable set point. This regulator is constructed so as tomove a specific volume of carbon dioxide without the loss of pressure onthe outlet side. All components of the pumping station utilize a novelcooling system which maintains carbon dioxide at a temperature wellbelow its critical temperature. This construction allows for both therefilling and the pumping of carbon dioxide at a known density andvolume, with repeatability when switching between pumping cylinders. Thecooling medium employed preferably comprises chilled water circulatingat a constant 20° C., which maintains the carbon dioxide at 25° C.Therefore, by maintaining a pressure of 2500 psi at 25°, a constantdensity of 0.906 gram/ml is achieved as well as maintaining the carbondioxide in its liquid phase.

In order to increase the solubility of the carbon dioxide Within thepolymer composition and achieve a resulting product having much finercell structure than can be achieved with conventional foamingtechniques, the temperature and pressure of the carbon dioxide must beheld well above its critical points at the injector. In accordance withthe present invention, the result is attained by employing a uniquelyconstructed injector depicted in FIG. 7.

As shown in FIG. 7, injector 40 is insulated with a fiber reinforcedphenolic sleeve 41 which preferably extends between about 60% and 100%of the injector length, from the barrel (heat source) to the injectionpoint. Preferably, injector 40 is held in place by retaining bolt orcollar 42. It has been found that the construction of injector 40 is ofparamount importance in maintaining the liquid phase of the carbondioxide just prior to injection.

Carbon dioxide typically becomes supercritical in the final 25% to 35%of the injector length before entering the melt stream. At this point,the back pressure within the extruder should be between about 1700 psiand 2000 psi, in order to maintain cell size of the final productbetween about 0.02 mm and 0.3 mm, with a cell density ranging betweenabout 25,000,000 cells/cm³ and 500,000 cells/cm³.

The third stage of the extruder is designed for pumping and cooling ofthe polymer melt. The screw in this last stage is basically constructedfor advancing the product through the system. Preferably, cross cuts areformed in the forward-mg blades, oriented in such a manner as to forcethe polymer melt from the lower areas within the melt pool at the rootof the screw into contact with the inner barrel wall, where a liquidcooling medium is circulated through a shell encompassing the entirecircumference of said barrel. This last stage must also maintain thepressure required (1700 psi to 2000 psi. at 104° C.) in order for thecarbon dioxide to be maintained in its supercritical phase and remainsolubilized within the polymer melt.

The gas laden polymer melt with its combination of polymer blends,nucleators, chemical blowing agents, and color concentrates now mustpass through a linear flow extrusion device 22 shown in FIGS. 1-3. Bythe nature of its design, taking into account polymer flowcharacteristics, the linear flow extrusion device 22 directs the polymerflow into multiple flow channels separating out portions of mottledpolymer 25, causing a unique random streaking effect. After passingthrough the die and associated adapters, and manipulated downstream, therandom streaking effect provides the desired aesthetic quality.

In the preferred construction, the linear flow extrusion device 22 has adual function by serving as a back pressure promoter and maintaining aspecific pressure through rheological calculations which give a specifichole size in the device versus a known throughput of polymer.

In accordance with the present invention, the extrudate from theextruder may be processed using a variety of alternate constructions. Asprovided herein, two alternate, unique and highly desirable processingsystems are detailed. Although these alternate constructions are definedin connection with the manufacture of synthetic closures for liquidbearing containers, such as wine bottles, both processes defined hereincan be employed for numerous alternate products. Consequently, thisdisclosure is provided for exemplary purposes and not as a limitation ofthe present invention.

In the preferred method, as shown in FIGS. 8-14, the extrudate isconveyed away from the exit portal or the die head of the extruder,which may be a conventional foaming die in the case of a total cellularproduct or a co-extrusion tool in the case of a composite structure,directly into “continuous motion casting apparatus” 60. As depicted,continuous motion casting apparatus 60 comprises two separate andindependent continuous loops 61 and 62, each of which comprise aplurality of interconnected polymer casting forms 63 and 64. In thepreferred construction, loop 61 comprises a plurality of polymer castingforms 63, each of which are identical to each other and areinterconnected on opposed sides to adjacent casting forms 63, therebyforming continuous closed loop 61.

Similarly, loop 62 comprises a plurality of polymer casting forms 64which are identical to each other and are interconnected on both sidesthereof to adjacent casting forms 64 to form continuous closed loop 62.In addition, each casting form 64 is a mirror image of casting form 63and is constructed for cooperative mating engagement with casting form63 to define a forming zone therewith in which the desired product iscontrollably produced.

In the preferred construction, each loop 61 and 62 continuously revolveabout two capstans, spaced about ten feet. In addition, loops 61 and 62are positioned in juxtaposed, spaced, cooperating relationship, assuringthat each polymer casting form 63 precisely matches and cooperatinglyengages with one polymer casting form 64 to establish therebetween aproduct forming zone 66, as shown in FIGS. 12, 13, and 14.

In the preferred construction, polymer casting forms 63 and 64 engagewith each other in cooperating relationship with the exit portal or diehead in order to receive the foamed polymer extrudate directly in cavity66. Thereafter, the casting forms remain engaged for the desired traveldistance, and are separated, when desired, to produce the fully formedproduct. Once separated, each polymer casting form 63 and 64 continuesto rotate in their respective closed loops 61 and 62, until returning tothe original position for another cycle.

Each set of casting forms 63 and 64 removes from the die lips theappropriate amount of extrudate on each retrieval. The shape defined byzone 66 in the casting form 63 and 64 will, when pressurized by theexpansion of the foaming extrudate, yield the formation of a fine cellelastomeric closure suitable for the stoppering of a wine bottle orother liquid bearing product. Preferably, casting forms 63 and 64 aremachined and maintained in alignment so that even with the pressureexerted by the expansion of the foam extrudate, no parting line can bedetected.

In the preferred construction, forms 63 and 64 are machined to include achamfer on both ends of the closure. In addition, a unique series ofparting or cutting tools are incorporated between each adjacent assemblyof casting forms and are constructed to cut or separate adjacentclosures in order to yield a perfectly sized synthetic closure.

This desired result is preferably accomplished by advancing the partingtools into association with cam means which moves the tool through theextrudate, leaving within casting form 63 and 64 and extruded fine cellelastomeric closure. By employing this construction, the discharge endof continuous motion casting apparatus 60 produces the finished closurein a continuous, mass-produced operation, with each product beingseparated during the cutting operation and expelled by the opening ofcasting forms 63 and 64.

In the preferred construction, casting forms 63 and 64 are cored for thecirculation of heat transfer fluids which, when utilized as a coolingmedium for the fine cell elastomeric foam will form a high density layerof elastomeric foam. In this way, when desired, an outer peripherallayer is effectively created on the surface of the resulting product. Bycreating a higher density outer layer or surface, a synthetic closure isproduced with resists the creasing effect of the corking machine jaws.

In an alternate construction, casting forms 63 and 64 may be constructedfor interconnection with a vacuum source. In this regard, a vacuum canbe applied through the use of minute machined orifices or through theuse of pores found in sintered metals which could be utilized as thematerial of construction for casting forms 63 and 64. The application ofvacuum further amplifies the intimate contact between the extrudate andthe casting forms to ensure equal cooling around the periphery of theclosure. This process ensures that the resulting synthetic closurecomprises the precisely desired cylindrical shape and dimensions.

Furthermore, if desired, casting forms 63 and 64 may comprise materialof construction which is textured by way of an etching process, creatingminute peaks and valleys on the surface in contact with the extrudate.This leads to a significant increase in the retention of surfacetreatments, such as silicone, parrafins, etc., while also imparting amore natural feel to the closure, such as a rough texture, as opposed toa smooth texture, which is extremely desirable in enhancing theuniqueness of the product and process.

In an alternate method, depicted in FIGS. 4 and 5, the extrudate isconveyed away from die 24 by way of a shaped or radiused belt conveyor(not shown) which moves extruder, 28 which is formed as an elongatedcontinuous foamed rod, trough a regulated cooling tunnel 45. Tunnel 45is maintained at a temperature of about 22° C., while regulating thespeed of the product independently of the final speed, in order toaccommodate the shrinkage factor of the foam as it cools andcrystallizes. In order to hasten the extrudate cooling process, a waterbath is employed by forced ambient air and then another water bathcontinuously used in succession. This method is particularly useful incooling medium to high density foams (100 to 500 kg/m³) since such foamsare extremely good insulators. It has been found that cooling theextrudate rapidly, followed by allowing heat internal to the foam tomake its way to the surface during the forced ambient air phase, andthen repeating to the rapid water cooling provides a substantially moreefficient system then conventional water cooling only.

In order to enhance the visual effect provided by incorporating colorconcentrates 25 to produce elongated colored strips or streaks 27, asdetailed above, this embodiment of the present invention incorporates atleast one pivot inducing plate 46, cooperatively associated with supportplate 47.

In the construction depicted in FIGS. 4 and 5, pivot inducing plate 46is connected by linking arm 48 to rotating disc 49. As a result of thisconstruction, the continuous rotation of disc 49 causes plate 46 tocontinuously move in a side to side or back and forth manner in ahorizontal plane, as represented by arrow 50.

By advancing extrudate or elongated foamed rod 28 along support plate48, with movable plate 47 in controlling contact or engagementtherewith, the side to side movement of plate 46 causes extrudate/rod 28to arcuately pivot along its central axis. This rolling, arcuate motioncauses the generally continuous horizontal streaks 27 formed in due 24to be formed into arcuately curved, sinusoidal patterns 27.

By creating curved or sinusoidal shaped streaks 27 in extrudate/rod 28,the finally produced, synthetic closure incorporates growth rings whichclosely emulate or simulate the growth rings commonly found in naturalcork products. As a result, the synthetic closure of the presentinvention is further enhanced and improved.

In the next step, the extrudate 28 is forwarded by means of a shaped,belted, pulling device known to those skilled in the art In the presentinvention, however, the pulling requires a precisely controlled speed,which works in conjunction with a non-contact method of measurement andcontrol. This construction is required in order to provide qualityassurance and dimensional stability, since the product diameter androundness must be maintained within + or −0.15 mm. These tighttolerances are absolutely essential in order to predict and controlextraction force and insertion level. In addition, extraction/insertiontreatment may be provided to assure optimum results.

An extremely precise cutter capable of achieving length control in theorder of + or −0.2 mm (0.008″) at line speeds approaching 2400 ft./hr isalso essential. These tolerances must be maintained, since variations inlength can affect head space within the bottle, which has a directcorrelation to movement of the closure out of the bottle and potentialpressure build up as wine changed density and/or volume withtemperature. In addition, length variations may also give the appearanceof a low filled bottle and, therefore, would be viewed as a negative bythe consumer.

Secondary Processes

After the primary phase is completed, several additional steps may berequired in order to impart desirable physical characteristics to theproduct which will be of assistance when used in high speed corkingsystems commonly found in the cork industry. One such step is thechamfering of the ends of the closure. If the bottling equipment beingemployed is older or does not receive the maintenance required tosustain the equipment in an excellent condition, a chamfered end isdesirable. In addition chamfering may be desirable from a purelyaesthetic point of view, as this operation provides the closure with afinished visual appearance.

If chamfered ends are desired, the formulation employed for the closuremust be capable of being cut or ground on both ends with customizedequipment. Generally, the chamfer comprises a width of between about 0.5to 1 mm, and is cut on an angle of about 45°. However, if desired, acustomized chamfer may also be produced.

Treatment

Traditionally, natural corks have been treated with substances that areintended to increase or decrease the co-efficient of friction of theclosure. As is well known, the closure must have the ability of beinginserted into the bottle with minimal force requirements being imposedon the equipment. In this way, the life of the equipment is increasedand the amount of maintenance required on the bottling lines isdecreased.

In addition, the closure must remain securely retained within the neckof the bottle until such time as the wine is opened. To accomplish thisgoal with a synthetic closure, the elastomeric foam must have theability to retain the additives or substances employed by the industryfor this purpose and must be able to use existing equipment andtechnology for the application of these treatments.

Typically, the substances employed are paraffinic in nature to increasethe coefficient of friction and silicone based oils to decrease thecoefficient of friction for the reasons stated above. It is possible,however, to incorporate these substances and use a pressure gradientprinciple as well as to allow for the “blooming” of these substances outof the polymers used to create the elastomeric foam and onto thesurface. Because of the many bottle types and the varying types ofcorking apparatus used in the industry, custom formulations withspecific amounts of these substances generally require the applicationto be accomplished through the use of existing equipment and technology.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said if all therebetween.

What we claim as new and desire to secure by Letters Patent is:
 1. Astopper or closure for a fluid product retaining container constructedfor being inserted and securely retained in a portal forming neck of thecontainer, said stopper/closure comprising: A. an elongated, solid,cylindrically shaped member dimensioned for insertion in the portal ofthe neck of the fluid product retaining container for closing andsealing the fluid product in the container; B. said member being formedfrom extruded foamed plastic material comprising a density rangingbetween about 100 kg/m³ to 500 kg/m³ and constructed for sealing thefluid product retained in the container and preventing transfer of thefluid product from the container prior to removal; and C. said foamedplastic material comprises a blend of at least formed two components,each comprising different hues or colors, thereby imparting anintegrally formed streaking effect to said synthetic closure; whereby asynthetic closure is attained which is capable of completely sealing anydesired fluid product in a container, retaining the product in thecontainer for any desired length of time without any degradation of thefluid product or degradation of the closure, while providing a visualappearance substantially identical to a stopper formed from naturalmaterial.
 2. The synthetic closure/stopper defined in claim 1, whereinthe cylindrically shaped member is further defined as comprisingsubstantially flat terminating surfaces forming the opposed ends of saidcylindrically shaped member.
 3. The synthetic closure/stopper defined inclaim 1, wherein the plastic material forming the core member is furtherdefined as comprising medium density or low density, closed cell, foamedplastic comprising one or more polymers selected from the groupconsisting of plastic polymers, inert polymers, homopolymers,copolymers, terpolymers, thermoplastic elastomers, and thermoplasticolefins.
 4. The synthetic closure/stopper defined in claim 3, whereinsaid closed cell foam plastic material is further defined as comprisingat least one polymer selected from the group consisting ofpolyethylenes, metallocene catalyst polyethylenes, polybutanes,polybutylenes, polyurethanes, silicones, vinyl-based resins, polyesters,ethylenic acrylic copolymers, ethylene-vinyl-acetate copolymers,ethylene-methyl-acrylate copolymers, ethylene-butyl-acrylate copolymers,ethylene-propylene-rubber, styrene butadiene rubber,ethylene-ethyl-acrylic copolymers, ionomers, polypropylenes, copolymersof polypropylene, copolymerizable ethylenically unsaturated comonomers,and thermoplastic amides.
 5. The synthetic closure/stopper defined inclaim 3, wherein said closed cell, foamed plastic material is furtherdefined as comprising one or more polyethylenes selected from the groupconsisting of high density, medium density, low density, linear lowdensity, ultra high density, and medium low density.
 6. The syntheticclosure/stopper defined in claim 5, wherein said member furthercomprises a density ranging between about 200 kg/m³ to 350 kg/m³.
 7. Thesynthetic closure/stopper defined in claim 1, wherein said member isfurther defined as comprising a. between about 10% and 60% by weightbased upon the weight of the entire member of at least one homopolymer,b. between about 10% and 60% by weight based upon the weight of theentire member of at least one thermoplastic elastomer, and c. betweenabout 10% and 60% by weight based upon the weight of the entire memberof at least one ionically cross-linked resin.
 8. The syntheticclosure/stopper defined in claim 7, wherein said core member is furtherdefined as comprising cell size ranging between about 0.02 mm and 0.5 mmand a cell density ranging between about 8,000,000 cells/cm³ to25,000,000 cells/cm³.
 9. The synthetic closure/stopper defined in claim1 wherein said member is further defined as being formed by extrusion.10. The synthetic closure/stopper defined in claim 9, wherein saidextrusion process is further defined as incorporating one or moreblowing agents selected from the group consisting of carbon dioxide,nitrogen, carbon, water, air nitrogen, helium, argon, AzodicarbonamicAzodiisobutyro-Nitride, Benzenesulfonhydrazide, 4,4-OxybenzeneSulfonylsemicarbazide, p-Toluene Sulfonylsemi-carbazide, BariumAzodicarboxlyate, N,N′-Dimethyl-N,N′-Dinitrosoterephthalamide,Trihydrazinotriazine, Aliphatic Hydrocarbons having 1-9 carbon atoms,Halogenated Aliphatic Hydrocarbons having 1-9 carbon atoms, Aliphaticalcohols having 1-3 carbon atoms partially Hydrogenated Chlorocarbon andChlorofluorocarbons.
 11. The synthetic closure/stopper defined in claim10, wherein said blowing agent is further defined as comprising betweenabout 0.005% and 10% by weight of the weight of the plastic material andcomprises an inert blowing agent selected from the group consisting ofnitrogen, carbon dioxide, water, air, nitrogen, helium, and argon. 12.The synthetic closure/stopper defined in claim 9, wherein a nucleatingagent is employed in the extrusion process and said nucleating agent isselected from the group consisting of calcium silicate, talc, clay,titanium oxide, silica, barium sulfate, diamatious earth, and mixturesof citric acid and sodium bicarbonate.
 13. The synthetic closure/stopperdefined in claim 12, wherein said nucleating agent is further defined ascomprising between about 1% and 10% by weight based upon the weight ofthe entire composition.
 14. The synthetic closure/stopper defined inclaim 1, wherein the outer surface of the member is further defined ascomprising indicia formed thereon.
 15. The synthetic closure/stopperdefined in claim 14, wherein said indicia comprises one or more selectedfrom the group consisting of letters, symbols, colors, graphics, andwood tones.
 16. The synthetic closure/stopper defined in claim 1,wherein said foamed plastic material comprises at least a firstcomponent having first hue and a second component having a second,different hue, and each of said components having different viscositiesand different melt flow indicies.
 17. The synthetic closure/stopperdefined in claim 16, wherein the melt flow index of the first componentranges between about 6 and 10, and the melt flow index of the secondcomponent ranges between about 16 and 20.